At present, several kinds of car locks are in use. One kind is removably mounted on the steering wheel and another kind is permanently fixed on the base of the steering wheel. Generally speaking, the former is preferred by most users, mainly because the former can be taken away off the steering wheel, and besides, directly forces a thief to give up his intention to steel the car. But most of the car locks mounted on the steering wheel have an extensible handle for hampering the steering wheel from being turned around, and a hook for hooking the circular body of the steering wheel. Said hook is commonly made of a tube, which is not so hard to prevent it from being illegally pried off by a thief.